Refrigerating system and refrigerating system control method

ABSTRACT

A refrigerating system of the present invention includes a plurality of parallel type refrigerators each of which has a plurality of compressors, and a host control device having a compressor start/stop permission output unit which is configured to output a compressor activation permission or a compressor stop permission to one of the plurality of parallel type refrigerators which is activated according to a predetermined permission condition. Each of the parallel-type refrigerators has a compressor activation control unit which is configured to a stopped compressor included in a certain refrigerator when a load factor of the certain refrigerator is equal to or greater than a first specified value and the compressor activation permission is received, and a compressor stop control unit which is configured to stop an activated compressor included in a certain refrigerator when the load factor of the certain refrigerator is less than a second specified value and the compressor stop permission is received.

TECHNICAL FIELD

The present invention relates to a refrigerating system and a refrigerating system control method.

Priority is claimed on Japanese Patent Application No. 2017-060970, filed Mar. 27, 2017, the content of which is incorporated herein by reference.

BACKGROUND ART

A parallel type refrigerator is a refrigerator having two compressors (for example, Patent Document 1). In a parallel type refrigerator as described in Patent Document 1, an operation is started by inputting an operation command, and one or two compressors are operated according to a load factor of the refrigerator. Switching of the number of operating compressors is performed by a determination process of a central processing unit (CPU) of the refrigerator itself or a starting and stopping operation by a person.

In heat source equipment in which a plurality of parallel type refrigerators are installed, when the plurality of refrigerators start and stop the compressor at the same timing according to determination of the refrigerators themself according to a fluctuation of a load of the heat source equipment, a temperature of cold water to be fed may greatly fluctuate. To prevent this temperature fluctuation, the starting and stopping operations have been performed by a person so far, and monitoring by a person is always required. As described above, in the case of a refrigerating system including the plurality of parallel type refrigerators which autonomously control an output, in each of the plurality of parallel type refrigerators, there is a problem that starting and stopping of each of the compressors included in each of the parallel type refrigerators may occur simultaneously.

CITATION LIST Patent Literature

[Patent Document 1]

Japanese Patent No. 5713570

SUMMARY OF INVENTION Technical Problem

An object of the present invention is to provide a refrigerating system and a refrigerating system control method which are able to prevent starting and stopping of a plurality of compressors from occurring simultaneously.

Solution to Problem

According to a first aspect of the present invention, a refrigerating system includes a plurality of parallel type refrigerators each of which has a plurality of compressors, and a host control device having a compressor start/stop permission output unit which is configured to output a compressor activation permission or a compressor stop permission to one of the plurality of parallel type refrigerators which is activated according to a predetermined permission condition, wherein each of the parallel type refrigerators includes a compressor activation control unit which is configured to activate a stopped compressor included in a certain refrigerator when a load factor of the certain refrigerator is equal to or greater than a first specified value and the compressor activation permission is received, and a compressor stop control unit which is configured to stop an activated compressor included in a certain refrigerator when the load factor of the certain refrigerator is less than a second specified value and the compressor stop permission is received.

According to a second aspect of the present invention, the compressor start/stop permission output unit is configured to output the next compressor activation permission or compressor stop permission after a predetermined activation permission waiting time or stop permission waiting time has elapsed when the compressor of the parallel type refrigerator is activated or stopped according to the compressor activation permission or the compressor stop permission.

According to a third aspect of the present invention, the host control device further includes a unit number control unit which is configured to or stops a main body of each of the parallel type refrigerators according to an output required for all of the plurality of parallel type refrigerators, when the main body is activated or stopped, the unit number control unit is configured to activate or stop the next main body after measurement of a predetermined stage increase prohibition time or stage decrease prohibition time ends, and the measurement of the stage increase prohibition time or the stage decrease prohibition time may be reset when the compressor of the parallel type refrigerator is activated or stopped according to the compressor activation permission or the compressor stop permission.

According to a fourth aspect of the present invention, the activation permission waiting time and the stop permission waiting time is shorter than the stage increase prohibition time and the stage decrease prohibition time.

According to a fifth aspect of the present invention, the compressor start/stop permission output unit is configured to output the compressor activation permission to the parallel type refrigerator having the highest priority among the parallel type refrigerators in which one or more of the compressors are not activated and is configured to output the compressor stop permission to the parallel type refrigerator having the lowest priority among the parallel type refrigerators in which two or more of the compressors are activated, when a predetermined malfunction occurs in the parallel type refrigerator which is activated, the priority of the parallel type refrigerator is set to be the lowest among the parallel type refrigerators which are activated, and when a predetermined malfunction occurs in the parallel type refrigerator which is stopped, the priority of the parallel type refrigerator is set to be the lowest among the parallel type refrigerators which are stopped.

According to a sixth aspect of the present invention, a refrigerating system control method uses a plurality of parallel type refrigerators each of which has a plurality of compressors, and a host control device having a compressor start/stop permission output unit which is configured to output a compressor activation permission or a compressor stop permission to one of the plurality of parallel type refrigerators which is activated according to a predetermined permission condition, wherein, in each of the parallel type refrigerators, a stopped compressor included in a certain refrigerator is activated by a compressor activation control unit when a load factor of the certain refrigerator is equal to or greater than a first specified value and the compressor activation permission is received, and an activated compressor included in a certain refrigerator is stopped by a compressor stop control unit when the load factor of the certain refrigerator is less than a second specified value and the compressor stop permission is received.

Advantageous Effects of Invention

According to the aspects of the present invention, it is possible to prevent starting and stopping of a plurality of compressors from occurring simultaneously.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a system diagram showing a whole constitution of a refrigerating system according to a first embodiment.

FIG. 2 is a block diagram showing a constitution example of a control unit provided in a control device 6, a parallel type refrigerator 11, and the like shown in FIG. 1.

FIG. 3 is a flowchart showing an operation example of the control unit 5 shown in FIG. 2.

FIG. 4 is a flowchart showing an operation example of a unit number control unit 612 shown in FIG. 2.

FIG. 5 is a flowchart showing an operation example of a compressor start and stop permission output unit 611 shown in FIG. 2.

FIG. 6 is a schematic diagram showing an operation example of the refrigerating system 1 shown in FIG. 1.

FIG. 7 is a schematic diagram showing an operation example of the refrigerating system 1 shown in FIG. 1.

FIG. 8 is a schematic diagram showing an operation example of the refrigerating system 1 shown in FIG. 1.

FIG. 9 is a schematic diagram showing an operation example of the refrigerating system 1 shown in FIG. 1.

FIG. 10 is an explanatory diagram showing an operation example of the refrigerating system 1 shown in FIG. 1.

FIG. 11 is a system diagram showing a whole constitution of a refrigerating system according to the second embodiment.

DESCRIPTION OF EMBODIMENTS First Embodiment

A refrigerating system according to a first embodiment will be described below with reference to FIGS. 1 to 10.

(Whole Constitution)

FIG. 1 is a system diagram showing a whole constitution of a refrigerating system 1 according to the first embodiment. The refrigerating system 1 includes parallel type refrigerators 11 and 12, cooling towers 21 and 22, cold water pumps 31 and 32, cooling water pumps 41 and 42, a host control device 6, temperature sensors 91 and 92, and a flow rate sensor 93.

The parallel type refrigerator 11 includes two compressors 11-1 a and 11-1 b, an evaporator 11-2, and a condenser 11-3. The parallel type refrigerator 11 includes a control unit (a control unit 5 in FIG. 2) (not shown), controls a temperature when cold water having been introduced into the evaporator 11-2 is delivered to a set temperature, and activates only one of the two compressors 11-1 a and 11-1 b or activates both in accordance with a fluctuation of a load by control of the control unit. The parallel type refrigerator 11 can change, for example, a rated output and power consumption by switching the number of compressors that are activated. The compressors 11-1 a and 11-1 b compress a refrigerant gas. The condenser 11-3 condenses a high-temperature and high-pressure gas refrigerant compressed by the compressors 11-1 a and 11-1 b. The evaporator 11-2 evaporates a liquid refrigerant decompressed through an expansion valve (not shown). Further, the cold water introduced from the equipment side through a main pipe 71 is introduced into the evaporator 11-2 from a cold water inlet of the evaporator 11-2 through the pipe 71, the cold water pump 31, and a pipe 73, and is delivered from a cold water outlet of the evaporator 11-2 and delivered to a main pipe 78 leading to the equipment side through a pipe 74. In the evaporator 11-2, the introduced cold water is cooled to a predetermined set temperature through exchange of heat between the cold water and a low-temperature and low-pressure liquid refrigerant and then delivered from the evaporator 11-2. On the other hand, cooling water circulates between the cooling tower 21 and the condenser 11-3 through pipes 81, 82 and 83 and the cooling water pump 41 and cools the refrigerant by exchanging heat with a high-temperature and high-pressure refrigerant. The cold water pump 31 and the cooling water pump 41 are operated while the parallel type refrigerator 11 is activated.

Like the parallel type refrigerator 11, the parallel type refrigerator 12 includes two compressors 12-1 a and 12-1 b, an evaporator 12-2, and a condenser 12-3. The parallel type refrigerator 12 includes a control unit (a control unit 5 in FIG. 2) (not shown), controls a temperature when the cold water having been introduced into the evaporator 12-2 is delivered to a set temperature, and activates only one of the two compressors 12-1 a and 12-1 b or activates both in accordance with a fluctuation of a load by control of the control unit. The parallel type refrigerator 12 can change, for example, a rated output and power consumption by switching the number of compressors that are activated. The compressors 12-1 a and 12-1 b compress a refrigerant gas. The condenser 12-3 condenses a high-temperature and high-pressure gas refrigerant compressed by the compressors 12-1 a and 12-1 b. The evaporator 12-2 evaporates a liquid refrigerant expanded by an expansion valve (not shown). Further, the cold water introduced from the equipment side through the main pipe 71 is introduced into the evaporator 12-2 from a cold water inlet of the evaporator 12-2 through a pipe 75, the cold water pump 32, and a pipe 76, and is delivered from a cold water outlet of the evaporator 12-2 and delivered to the main pipe 78 leading to the equipment side through a pipe 77. In the evaporator 12-2, the introduced cold water is cooled to a predetermined set temperature through exchange of heat between the cold water and a low-temperature and low-pressure liquid refrigerant and then delivered from the evaporator 12-2. On the other hand, the cooling water circulates between the cooling tower 22 and the condenser 12-3 through pipes 84, 85 and 86 and the cooling water pump 42 and cools the refrigerant by exchanging heat with a high-temperature and high-pressure refrigerant. The cold water pump 32 and the cooling water pump 42 are operated while the parallel type refrigerator 12 is activated.

Further, the host control device 6 includes, for example, a computer, an input/output device and a communication device and inputs a main pipe return water temperature detected by the temperature sensor 91, a main pipe delivery water temperature detected by the temperature sensor 92, and a main pipe flow rate detected by the flow sensor 93. The host controller 6 controls start and stop (activation and stop) of main bodies of the parallel type refrigerators 11 and 12 and start and stop (activation and stop) of the compressors 11-1 a and 11-1 b and 12-1 a and 12-1 b by transmitting/receiving a predetermined control signal to/from the parallel type refrigerator 11 and the parallel type refrigerator 12 via a signal line or a communication line (not shown).

A constitution example shown in FIG. 1 is an example of the refrigerating system 1 according to the embodiment, and, for example, three or more parallel type refrigerators 11 and 12 may be provided. Further, the refrigerating system 1 may include a refrigerator which is not the parallel type refrigerator and includes, for example, only one compressor. Moreover, the parallel type refrigerator 11 is not limited to including the two compressors and may include three or more compressors.

Next, with reference to FIG. 2, a constitution example of the control unit (the control unit 5 in FIG. 2; not shown in FIG. 1) provided in each of the host control device 6 and the parallel type refrigerators 11 and 12 will be described. FIG. 2 is a block diagram for explaining the constitution example of the control unit 5 provided in each of the host control device 6 and the parallel type refrigerators 11 and 12. In addition, the same reference numerals are used for structures that are same as those shown in FIG. 1 (this applies to each drawing below).

The control unit 5 shown in FIG. 2 is, for example, a computer such as a microcomputer and includes a CPU, volatile and nonvolatile storage devices, an input/output device, a communication device, and the like which are not shown. The control unit 5 includes a compressor activation control unit 51, a compressor stop control unit 52, and a cold water temperature control unit 53. The compressor activation control unit 51, the compressor stop control unit 52 and the cold water temperature control unit 53 are functions realized by the CPU executing a predetermined program using hardware of the control unit 5.

The compressor activation control unit 51 activates a stopped compressor (for example, the compressor 11-1 b or the compressor 12-1 b) included in a certain refrigerator (the parallel type refrigerator 11 or the parallel type refrigerator 12) when a load factor of the certain refrigerator is equal to or higher than a first specified value (for example, 50%) and a compressor activation permission which will be described later is received from the host control device 6. The compressor stop control unit 52 stops an activated compressor (for example, the compressor 11-1 b or the compressor 12-1 b) included in a certain refrigerator (the parallel type refrigerator 11 or the parallel type refrigerator 12) when the load factor of the certain refrigerator (the parallel type refrigerator 11 or the parallel type refrigerator 12) is less than a second specified value (for example, 40%) and a compressor stop permission which will be described later is received from the host control device 6. The cold water temperature control unit 53 controls each unit of the parallel type refrigerator 11 or the parallel type refrigerator 12 so that a temperature of the cold water delivered from the evaporator 11-2 or the evaporator 12-2 coincides with a predetermined set value (for example, 7° C.).

The load factor of the parallel type refrigerator 11 or the parallel type refrigerator 12 is the following value. That is, the load factor of the “parallel type refrigerator” is a value determined according to a temperature difference between the cold water inlet (a sensor value of a temperature of the return water) and outlet (a sensor value of a temperature of the delivery water or a set outlet temperature (a target value of the temperature of the delivery water)) of the evaporator 11-2 or evaporator 12-2×a flow rate and can be obtained from an equation (load factor=temperature difference×flow rate×coefficient/rated output of parallel type refrigerator). Here, the coefficient is a constant determined by cold water specific heat or the like.

The host control device 6 includes a control unit 61. The host control device 6 may include an input/output device such as a display device, a printing device, a keyboard or a mouse as a part of the control unit 61 or as a peripheral device. The control unit 61 is a computer such as a server, a personal computer, or a microcomputer and includes a CPU, volatile and non-volatile storage devices, an input/output device, a communication device, and the like which are not shown. The control unit 61 includes a compressor start/stop permission output unit 611 and a unit number control unit 612. The compressor start/stop permission output unit 611 and the unit number control unit 612 are functions realized by the CPU executing a predetermined program using hardware of the control unit 61. The host control device 6 is connected to each of the control units 5 of the parallel type refrigerator 11 and the parallel type refrigerator 12 via a communication line (or signal line group) 60.

The compressor start/stop permission output unit 611 outputs the compressor activation permission or the compressor stop permission to one of the plurality of parallel type refrigerators 11 and 12 that is activated according to a predetermined permission condition. In each of the parallel type refrigerators 11 and 12, the compressor activation permission is a signal which permits (enables) activation control of the compressor (for example, the compressor 11-1 b or the compressor 12-1 b) according to the load factor for each of the parallel type refrigerators 11 and 12. The compressor activation permission is output to a parallel type refrigerator in which at least one of the plurality of compressors is activated and a stopped compressor is present. Further, the compressor stop permission is output to a parallel type refrigerator in which at least two of the plurality of compressors are activated. Each of the parallel type refrigerators 11 and 12 can activate its own compressor (for example, the compressor 11-1 b or the compressor 12-1 b) according to its own load factor only during a period when the compressor activation permission is output to it. Also, in each of the parallel type refrigerators 11 and 12, the compressor stop permission is a signal which permits (enables) stop control of the compressor (for example, the compressor 11-1 b or the compressor 12-1 b) according to the load factor for each of the parallel type refrigerators 11 and 12. Each of the parallel type refrigerators 11 and 12 can stop its own compressor (for example, the compressor 11-1 b or the compressor 12-1 b) according to its own load factor only during a period when the compressor stop permission is output to it.

The unit number control unit 612 performs the activation or stop of each main body of the parallel type refrigerators 11 and 12 according to an output required for the plurality of parallel type refrigerators 11 and 12 as a whole. Here, the output required for the whole can be defined according to a required heat amount (a required heat absorption amount), a flow rate, both the required heat amount and the flow rate, the temperature (the temperature of the return water) of the cold water introduced from the main pipe 71, and the like. Here, the required heat amount is a value determined according to a temperature difference between a temperature (a sensor value) of the cold water returned from the equipment side via the main pipe 71 and a temperature (a sensor value) of the cold water delivered to the equipment side via the main pipe 78 or a set temperature (a target value of the temperature), and a flow rate of the cold water delivered to the equipment side through the main pipe 78. Furthermore, the flow rate is a value determined according to the flow rate of the cold water delivered to the equipment side through the main pipe 78. In addition, the unit number control unit 612 sets priority in activating or stopping the plurality of parallel type refrigerators 11 and 12 in advance. In the following description, it is assumed that the priority of the parallel type refrigerator 11 is set higher than the priority of the parallel type refrigerator 12.

Next, an operation example of the control unit 5 shown in FIG. 2 will be described with reference to FIG. 3. A process shown in FIG. 3 is repeatedly performed in each of the control units 5, for example, at a constant cycle. In the process shown in FIG. 3, first, the control unit 5 (for example, the cold water temperature control unit 53) calculates the above-described load factor of the certain refrigerator (Step S101). Next, the compressor activation control unit 51 determines whether or not the load factor calculated in Step S101 is equal to or greater than the first specified value (for example, 50%) (Step S102). When the load factor is equal to or greater than the first specified value (for example, 50%) (in the case of “Y” in Step S102), the compressor activation control unit 51 determines whether or not the compressor activation permission is received from the host control device 6 (Step S103). When the compressor activation permission is received from the host control device 6 (in the case of “Y” in Step S103), the compressor activation control unit 51 activates the stopped compressor (for example, the compressor 11-1 b or the compressor 12-1 b) (Step S104). Next, the compressor activation control unit 51 notifies the host controller 6 that the compressor has been activated (Step S105).

On the other hand, when the load factor is not equal to or greater than the first specified value (for example, 50%) (in the case of “N” in Step S102), the compressor activation control unit 51 determines whether or not the load factor calculated in Step S101 is less than the second specified value (for example, 40%) (Step S106). When the load factor is less than the second specified value (for example, 40%) (in the case of “Y” in Step S106), the compressor activation control unit 51 determines whether or not the compressor stop permission is received from the host control device 6 (Step S107). When the compressor stop permission is received from the host control device 6 (in the case of “Y” in Step S107), the compressor activation control unit 51 stops the activated compressor (for example, the compressor 11-1 b and the compressor 12-1 b) (Step S108). Next, the compressor activation control unit 51 notifies the host controller 6 that the compressor has been stopped (Step S109).

In addition, when the load factor is not less than the second specified value (for example, 40%) (in the case of “N” in Step S106), when the compressor activation permission is not received from the host control device 6 (in the case of “N” in Step S103), or when the compressor stop permission is not received from the host control device 6 (in the case of “N” in Step S107), the process shown in FIG. 3 is terminated without activating or stopping the compressor by the control unit 5.

Due to the process shown in FIG. 3, the control unit 5 can activate or stop the compressor according to the load factor of the certain refrigerator only when the activation or stop is permitted from the host control device 6. That is, the host control device 6 can prevent the activation and stop of the compressors from being simultaneously performed in the plurality of parallel type refrigerators 11 or 12 by outputting the compressor activation permission and the compressor stop permission to one parallel type refrigerator 11 or 12. The host control device 6 outputs the compressor activation permission to the parallel type refrigerator in which one or more compressors are activated and which has the stopped compressor and outputs the compressor stop permission to the parallel type refrigerator which has two or more activated compressors.

Next, an operation example of the unit number control unit 612 shown in FIG. 2 will be described with reference to FIG. 4. A process shown in FIG. 4 is repeatedly performed in the unit number control unit 612, for example, at a constant cycle. In the embodiment, a stage increase prohibition time and a stage decrease prohibition time are set for the stage increase and the stage decrease to prevent a continuous increase (a stage increase) and decrease (a stage decrease) in the number of activated parallel type refrigerators. After the stage increase or the stage decrease is performed, measurement of the stage increase prohibition time and the stage decrease prohibition time is started, and the next stage increase or the stage decrease is prohibited until the measurement ends. The measurement of the stage increase prohibition time and the stage decrease prohibition time is reset and then started, for example, when the host control device 6 is activated. Also, the stage increase prohibition time and the stage decrease prohibition time may be the same or different.

In the process shown in FIG. 4, first, the unit number control unit 612 acquires the main pipe return water temperature detected by the temperature sensor 91, the main pipe delivery water temperature detected by the temperature sensor 92, and the main pipe flow rate detected by the flow sensor 93 and then calculates the required output (Step S201). Next, the unit number control unit 612 determines whether or not a predetermined stage increase condition is satisfied (Step S202). For example, when the rated output of the parallel type refrigerator which is activated and the flow rate of the cold water pump which is activated are not sufficient for the required output and the parallel type refrigerator which is stopped and can be activated remains, the stage increase condition is satisfied.

When the predetermined stage increase condition is satisfied (in the case of “Y” in Step S202), the unit number control unit 612 determines whether or not the measurement of the stage increase prohibition time has ended (Step S203). When the measurement of the stage increase prohibition time has ended (in the case of “Y” in Step S203), the unit number control unit 612 activates the parallel type refrigerator having the highest priority (step S204). In Step S204, for example, the unit number control unit 612 transmits a predetermined control signal to the parallel type refrigerator having the highest priority, thereby instructing to activate one compressor and to activate a refrigeration cycle. Next, the unit number control unit 612 resets the measurement of the stage increase prohibition time and then starts the measurement of the stage increase prohibition time (Step S205). Next, the unit number control unit 612 resets the measurement of the stage decrease prohibition time and then starts the measurement of the stage decrease prohibition time (Step S206). Next, the unit number control unit 612 resets measurement of an activation permission waiting time and then starts the measurement of the activation permission waiting time (Step S207). Next, the unit number control unit 612 resets measurement of a stop permission waiting time and then starts the measurement of the stop permission waiting time (Step S208). Here, the activation permission waiting time and the stop permission waiting time are prohibition periods set when the compressor is activated or stopped. While the stage increase prohibition time and the stage decrease prohibition time are the prohibition periods related to the activation and stop of the main body of the parallel type refrigerator, the activation permission waiting time and the stop permission waiting time are the prohibition periods related to the activation and stop of the compressor.

On the other hand, when the predetermined stage increase condition is not satisfied (in the case of “N” in Step S202), the unit number control unit 612 determines whether or not the predetermined stage decrease condition is satisfied (Step S209). For example, when the rated output of the parallel type refrigerator which is activated and the flow rate of the cold water pump which is activated are too large for the required output and the parallel type refrigerator which is activated and can be stopped is present, the stage decrease condition is satisfied. When the predetermined stage decrease condition is satisfied (in the case of “Y” in Step S209), the unit number control unit 612 determines whether or not the measurement of the stage decrease prohibition time has ended (Step S210). When the measurement of the stage decrease prohibition time has ended (in the case of “Y” in Step S210), the unit number control unit 612 stops the parallel type refrigerator having the lowest priority (Step S211). In Step S211, for example, the unit number control unit 612 transmits a predetermined control signal to the parallel type refrigerator having the lowest priority, thereby instructing to stop the compressor and to stop the refrigeration cycle. Next, the unit number control unit 612 resets the measurement of the stage decrease prohibition time and then starts the measurement of the stage decrease prohibition time (Step S212). Next, the unit number control unit 612 resets the measurement of the stage increase prohibition time and then starts the measurement of the stage increase prohibition time (Step S213). Next, the unit number control unit 612 resets the measurement of the activation permission waiting time and then starts the measurement of the activation permission waiting time (Step S214). Next, the unit number control unit 612 resets the measurement of the stop permission waiting time and then starts the measurement of the stop permission waiting time (Step S215).

Further, when the measurement of the stage increase prohibition time has not ended (in the case of “N” in Step S203), when the predetermined stage decrease condition is not satisfied (in the case of “N” in Step S209), or when the measurement of the stage decrease prohibition time has not ended (in the case of “N” in Step S210), the unit number control unit 612 terminates the process shown in FIG. 4 without activating or stopping the parallel type refrigerator.

Due to the process shown in FIG. 4, the unit number control unit 612 provides the stage increase prohibition time and the stage decrease prohibition time and then can activate and stop the parallel type refrigerator according to the output required for all of the parallel type refrigerators 11 and 12.

Next, an operation example of the compressor start/stop permission output unit 611 shown in FIG. 2 will be described with reference to FIG. 5. A process shown in FIG. 5 is repeatedly performed in the compressor start/stop permission output unit 611, for example, at a constant cycle. Also, in the embodiment, the measurement of the activation permission waiting time and the stop permission waiting time provided to prohibit the activation and stop of the compressor from occurring continuously is reset and started, for example, when the host control device 6 is activated. The activation permission waiting time and the stop permission waiting time may be the same or different.

In the process shown in FIG. 5, first, the compressor start/stop permission output unit 611 determines whether or not a compressor activation permission ON condition is satisfied (Step S301). In the process shown in FIG. 5, the compressor activation permission ON condition (Step S301) and a compressor stop permission ON condition (Step S304) differ according to a type of the required output which is used in the determination of Step S201 by the unit number control unit 612. As described above, the type of the required output includes a case in which it is related to the heat amount (hereinafter referred to as a heat amount mode), a case in which it is related to the flow rate (hereinafter referred to as a flow rate mode), a case in which it is related to the heat amount and the flow rate (hereinafter referred to as a heat amount+flow rate mode), and a case in which it is related to the return temperature (hereinafter referred to as a return temperature mode). Among them, in the case in which it is related to the flow rate (in the case of the flow rate mode and the heat amount+flow rate mode), since the activation and stop of the parallel type refrigerators 11 and 12 and the activation and stop of the cold water pumps 31 and 32 are interlocked, it may be required to prioritize adjustment of the rated output and the flow rate by activating or stopping the parallel type refrigerator over adjustment of the rated output or the power consumption by activating or stopping the compressor to satisfy the requirement of the flow rate. Therefore, in the embodiment, in the heat amount mode and the return temperature mode, the compressor is activated or stopped so that the number of parallel type refrigerators that are activated is as small as possible. On the other hand, in the flow rate mode and the heat amount+flow rate mode, priority is given to increasing the number of activations of the parallel type refrigerator over increasing the number of activations of the compressor. Thus, conditions for permitting the activation or stop of the compressor vary according to a mode difference and an activation status of the parallel type refrigerator.

As described above, in Step S301, the compressor start/stop permission output unit 611 determines whether or not the compressor activation permission ON condition is satisfied according to the mode. When the compressor activation permission ON condition is satisfied (in the case of “Y” in Step S301), that is, when a condition that it is desirable to output (ON) the compressor activation permission to the parallel type refrigerator which is activated and has the highest priority is satisfied, the compressor start/stop permission output unit 611 determines whether or not the activation permission waiting time has elapsed (Step S302). When the activation permission waiting time has elapsed (in the case of “Y” in Step S302), the compressor start/stop permission output unit 611 outputs the compressor activation permission to the parallel type refrigerator which is activated and has the highest priority (Step S303).

On the other hand, when the compressor activation permission ON condition is not satisfied (in the case of “N” in Step S301), the compressor start/stop permission output unit 611 determines whether or not the compressor stop permission ON condition is satisfied (Step S304). In the case in which the compressor stop permission ON condition is satisfied (in the case of “Y” in Step S304), when a condition that it is desirable to output (ON) the compressor stop permission to the parallel type refrigerator in which a plurality of compressors are activated and which has the lowest priority is satisfied, the compressor start/stop permission output unit 611 determines whether or not the stop waiting time has elapsed (Step S305). When the stop permission waiting time has elapsed (in the case of “Y” in step S305), the compressor stop permission is output (ON) to the parallel type refrigerator in which the plurality of compressors are activated and which has the lowest priority (Step S306).

After Steps S303 and S306, the compressor start/stop permission output unit 611 determines whether or not a permission reset condition is satisfied (Step S307). Satisfaction of the permission reset condition means that a predetermined event which is not the activation or stop of the compressor permitted by the compressor activation permission output in Step S303 or the compressor stop permission output in Step S306 has occurred. For example, when an event such as a compressor being stopped due to a failure, a compressor which is not permitted being activated by a manual operation, or a communication error with a refrigerator to which an instruction is scheduled to be output occurs, the permission reset condition is satisfied. When the permission reset condition is satisfied (in the case of “Y” in Step S307), the compressor start/stop permission output unit 611 stops the output of the compressor activation permission or the compressor stop permission which is being output (Step S311).

On the other hand, when the permission reset condition is not satisfied (in the case of “N” in Step S307), the compressor start/stop permission output unit 611 determines whether or not it is detected that a compressor activation notification or a compressor stop notification is received from a parallel type refrigerator to which the compressor activation permission or the compressor stop permission is output (Step S308). When it is not detected (in the case of “N” in Step S308), the compressor start/stop permission output unit 611 performs the determination process of Step S307. Additionally, when the permission reset condition is not satisfied (in the case of “N” in Step S307), the compressor start/stop permission output unit 611 determines again whether or not it is detected that the compressor activation notification or the compressor stop notification is received (Step S308). Thereafter, when the permission reset condition is not satisfied, the compressor start/stop permission output unit 611 repeatedly performs the determination process of Step S308 until the compressor activation notification or the compressor stop notification is received.

Additionally, when it is detected (in the case of “Y” in Step S308), the compressor start/stop permission output unit 611 resets measurement of an activation waiting time and the stop permission waiting time and then starts the measurement of the activation waiting time and the stop permission waiting time (Step S309). Next, the compressor start/stop permission output unit 611 resets the measurement of the stage increase prohibition time and the stage decrease prohibition time and then starts the measurement of the stage increase prohibition time and the stage decrease prohibition time (Step S310). Next, the compressor start/stop permission output unit 611 stops the output of the compressor activation permission or the compressor stop permission which is being output (Step S311).

Further, when the activation permission waiting time has not elapsed (in the case of “N” in Step S302), the compressor stop permission ON condition is not satisfied (in the case of “N” in Step S304), and the stop permission waiting time has not elapsed (in the case of “N” in Step S305), the compressor start/stop permission output unit 611 terminates the process shown in FIG. 5 without outputting the compressor activation permission or the compressor stop permission.

Due to the process shown in FIG. 5, since the compressor start/stop permission output unit 611 provides the activation permission waiting time and the stop permission waiting time and then permits any one of the plurality of parallel type refrigerators 11 and 12 to activate or stop the compressor, it is possible to prevent the activation or stop of each of the compressors included in each of the parallel type refrigerators from occurring simultaneously or continuously in a short time.

Further, in the process shown in FIG. 5, when the activation or stop of the compressor is detected, the compressor start/stop permission output unit 611 resets the measurement of the stage increase prohibition time and the stage decrease prohibition time and then starts the measurement of the stage increase prohibition time and the stage decrease prohibition time. Therefore, it is possible to prevent the activation or stop of each of the main bodies of the parallel type refrigerators and the activation or stop of each of the compressors from occurring simultaneously or continuously in a short time.

Hunting between compressor start/stop control and unit number control can be prevented by setting the activation permission waiting time and the stop permission waiting time to be shorter than the stage increase prohibition time and the stage decrease prohibition time.

Next, an example of the compressor start/stop control and the unit number control in the refrigerator system 1 shown in FIG. 1 will be described with reference to FIGS. 6 to 9. FIG. 6 shows an operation example when the unit number control is set to the heat amount mode and the output required for the whole tends to increase from (a) toward (f). FIG. 7 shows an operation example when the unit number control is set to the heat amount mode and the output required for the whole tends to decrease from (a) toward (f). FIG. 8 shows an operation example when the unit number control is set to the flow rate mode and the output required for the whole tends to increase from (a) toward (f). FIG. 9 shows an operation example when the unit number control is set to the flow rate mode and the output required for the whole tends to decrease from (a) toward (f).

In the example shown in FIG. 6, in FIG. 6(a), the main body of the parallel type refrigerator 11 is activated, and the main body of the parallel type refrigerator 12 is stopped. Further, in the parallel type refrigerator 11, the compressor 11-1 a is activated and the compressor 11-1 b is stopped. When the necessary output therefor increases, the compressor activation permission ON condition is satisfied (“Y” in Step S301), and the compressor activation permission is output to the parallel type refrigerator 11 which has the compressor that is activated and can be activated and has the highest priority (Step S303) (FIG. 6(a)). Additionally, as shown in FIG. 6(b), the compressor 11-1 b is activated. When the necessary output therefor increases, (or, when it is not sufficient to activate the compressor 11-1 b), an activation instruction is output to the parallel type refrigerator 12 having the next priority, as shown in FIG. 6(c). Then, as shown in FIG. 6(d), the main body of the parallel type refrigerator 12 is activated, and the compressor 12-1 a is activated with the activation of the main body. When the necessary output therefor increases (or when it is not sufficient to activate the compressor 12-1 a), the compressor activation permission ON condition is satisfied (“Y” in Step S301), and the compressor activation permission is output to the parallel type refrigerator 12 which has the compressor that is activated and can be activated and has the highest priority (Step S303) (FIG. 6(e)). Then, as shown in FIG. 6(f), the compressor 12-1 b is activated.

On the other hand, in the example shown in FIG. 7, in FIG. 7(a), both the main body of the parallel type refrigerator 11 and the main body of the parallel type refrigerator 12 are activated. Further, in the parallel type refrigerator 11, the compressor 11-1 a and the compressor 11-1 b are activated, and in the parallel type refrigerator 12, the compressor 12-1 a and the compressor 12-1 b are activated. When the necessary output therefor decreases, the compressor stop permission ON condition is satisfied (“Y” in Step S304), the compressor stop permission is output to the parallel type refrigerator 12 which has a plurality of compressors that are activated and can be stopped and has the lowest priority (Step S306) (FIG. 7(a)). Additionally, as shown in FIG. 7(b), the compressor 12-1 b stops. When the necessary output therefor decreases (or when it is not sufficient to stop the compressor 12-1 b), as shown in FIG. 7(c), a stop instruction is output to the parallel type refrigerator 12 having the lowest priority. Then, as shown in FIG. 7(d), the main body of the parallel type refrigerator 12 stops. When the necessary output therefor decreases (or when it is not sufficient to stop the compressor 12-1 a), the compressor stop permission ON condition is satisfied (“Y” in Step S304), and the compressor stop permission is output to the parallel type refrigerator 11 which has a plurality of compressors that are activated and can be stopped and has the lowest priority (Step S306) (FIG. 7(e)). Then, as shown in FIG. 7(f), the compressor 11-1 b is stopped.

In the example shown in FIG. 8, in FIG. 8(a), the main body of the parallel type refrigerator 11 is activated, and the main body of the parallel type refrigerator 12 is stopped. Further, in the parallel type refrigerator 11, the compressor 11-1 a is activated, and the compressor 11-1 b is stopped. When the necessary output therefor increases, as shown in FIG. 8(a), an activation command is output to the parallel type refrigerator 12 which has the compressor that is stopped and can be activated and has the next priority. Additionally, as shown in FIG. 8(b), the main body of the parallel type refrigerator 12 is activated, and the compressor 12-1 a is activated with the activation of the main body. When the necessary output therefor increases (or when it is not sufficient to activate the compressor 12-1 a), the compressor activation permission ON condition is satisfied (“Y” in Step S301), and the compressor activation permission is output to the parallel type refrigerator 11 which has the compressor that is activated and can be activated and has the highest priority (Step S303) (FIG. 8(c)). Then, as shown in FIG. 8(d), the compressor 11-1 b is activated. When the necessary output therefor increases (or when it is not sufficient to activate the compressor 11-1 a), the compressor activation permission ON condition is satisfied (“Y” in Step S301), and the compressor activation permission is output to the parallel type refrigerator 12 which has the compressor that is activated and can be activated and has the highest priority (Step S303) (FIG. 8(e)). Then, as shown in FIG. 8(f), the compressor 12-1 b is activated.

On the other hand, in the example shown in FIG. 9, in FIG. 9(a), both the main body of the parallel type refrigerator 11 and the main body of the parallel type refrigerator 12 are activated. Further, in the parallel type refrigerator 11, the compressor 11-1 a and the compressor 11-1 b are activated, and in the parallel type refrigerator 12, the compressor 12-1 a and the compressor 12-1 b are activated. When the necessary output therefor decreases, the compressor stop permission ON condition is satisfied (“Y” in Step S304), the compressor stop permission is output to the parallel type refrigerator 12 which has a plurality of compressors that are activated and can be stopped and has the lowest priority (Step S306) (FIG. 9(a)). Additionally, as shown in FIG. 9(b), the compressor 12-1 b stops. When the necessary output therefor decreases (or when it is not sufficient to stop the compressor 12-1 b), the compressor stop permission ON condition is satisfied (“Y” in Step S304), the compressor stop instruction is output to the parallel type refrigerator 11 which has a plurality of compressors that are activated and can be stopped and has the lowest priority (Step S306) (FIG. 9(c)). Then, as shown in FIG. 9(d), the compressor 11-1 b stops. When the necessary output therefor decreases (or when it is not sufficient to stop the compressor 11-1 b), the stop instruction is output to the parallel type refrigerator 12 having the lowest priority (FIG. 9 (e)). Then, as shown in FIG. 9(f), the main body of the parallel type refrigerator 12 stops.

As shown in FIGS. 6 to 9, it is possible to appropriately set the priority of the activation or stop of the compressor and the activation or stop of the main body by appropriately setting the compressor activation permission ON condition or the compressor stop permission ON condition according to the mode difference.

Next, with reference to FIG. 10, an example of setting the priority in the unit number control when a malfunction such as a failure occurs will be described. In FIG. 10, “→X→” indicates occurrence of a failure in one compressor. Further, in the example shown in FIG. 10, at the time of activation, the activation is started from the parallel type refrigerator which is stopped and has a small number assigned to priority. Also, at the time of stop, the stop is started from the parallel type refrigerator which is activated and has a large number assigned to priority. Further, when a predetermined malfunction occurs in a parallel type refrigerator which is activated, the priority of the parallel type refrigerator is set to be the lowest among the parallel type refrigerators which are activated. Further, when a predetermined malfunction occurs in a parallel type refrigerator which is stopped, the priority of the parallel type refrigerator is set to be the lowest among the parallel type refrigerators which are stopped. As shown in FIG. 10, by changing the priority when a malfunction occurs, an output fluctuation (a temperature fluctuation, or the like) at the time of occurrence of the malfunction can be curbed.

Modified Example

Although the refrigerating system 1 according to the first embodiment has been described in detail, specific aspects of the refrigerating system 1 are not limited to the above-described embodiment, and various design changes and the like can be added without departing from the scope of the invention.

For example, in the first embodiment, for example, the priority in the unit number control can be changed according to an integration time to equalize an operation integration time for each of the parallel type refrigerators or compressors. Further, an integration time of a compressor having a long integration operation time among the plurality of compressors can be adopted, or an average value of integration times of the plurality of compressors can be adopted as the integration time.

Moreover, the control device 6 can also be mounted, for example, in any one or a plurality of the control units 5.

Second Embodiment

FIG. 11 is a system diagram showing the entire constitution of a refrigerating system 1 a according to a second embodiment. In addition, the same reference numerals are provided to the same structures as those shown in FIG. 1, and descriptions thereof will be omitted. The refrigerating system 1 a includes a cold water pump 31 a and a cold water pump 31 b connected in parallel, instead of the cold water pump 31 shown in FIG. 1. Further, the refrigerating system 1 a includes a cooling water pump 41 a and a cooling water pump 41 b connected in parallel, instead of the cooling water pump 41 shown in FIG. 1. Further, the activation and stop of the cold water pump 31 a and the cooling water pump 41 a are interlocked with the activation and stop of the compressor 11-1 a. Further, the activation and stop of the cold water pump 31 b and the cooling water pump 41 b are interlocked with the activation and stop of the compressor 11-1 b. Also, the refrigerating system 1 a includes a cold water pump 32 a and a cold water pump 32 b connected in parallel, instead of the cold water pump 32 shown in FIG. 1. Further, the refrigerating system 1 a includes a cooling water pump 42 a and a cooling water pump 42 b connected in parallel, instead of the cooling water pump 42 shown in FIG. 1. Further, the activation and stop of the cold water pump 32 a and the cooling water pump 42 a are interlocked with the activation and stop of the compressor 12-1 a. Further, the activation and stop of the cold water pump 32 b and the cooling water pump 42 b are interlocked with the activation and stop of the compressor 12-1 b.

In the refrigerating system 1 a, when the activation or stop of the compressor 11-1 a or 11-1 b and the compressor 12-1 a or 12-1 b is determined, it is desirable to consider operation states of the cold water pump 31 a and the cold water pump 31 b or the cooling water pump 41 a and the cooling water pump 41 b, or operation states of the cold water pump 32 a and the cold water pump 32 b or the cooling water pump 42 a and the cooling water pump 42 b. That is, it is desirable to set a determination condition of the activation permission or stop permission of each of the compressors in consideration of a change in a flow rate caused by turning on or off the respective pumps.

In each of the above-described embodiments, various processes of the above-described control unit 5 or control unit 61 are stored in a computer-readable recording medium in the form of a program. The various processes are performed by the computer reading and executing the program. Further, the computer-readable recording medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Also, the computer program may be distributed to a computer via a communication line, and the computer which has received the distribution may execute the program.

The program may be for realizing a part of the above-described functions. Furthermore, the program may be a so-called differential file (a differential program) which can realize the above-described functions in combination with a program already recorded in the computer system. Also, each of the control unit 5 and the control unit 61 may be constituted by a single computer or may be constituted by a plurality of computers connected to be communicable.

As described above, although several embodiments according to the present invention have been described, all the embodiments are presented as examples and are not intended to limit the scope of the invention. The embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. The embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof as well as included in the scope and gist of the invention.

INDUSTRIAL APPLICABILITY

According to the refrigerating system and the refrigerating system control method, it is possible to prevent the activation or stop of the plurality of compressors from occurring simultaneously.

REFERENCE SIGNS LIST

-   -   1, 1 a Refrigerating system     -   11, 12 Parallel type refrigerator     -   11-1 a, 11-1 b, 12-1 a, 12-1 b Compressor     -   11-2 Evaporator     -   11-3 Condenser     -   5 Control unit     -   51 Compressor activation control unit     -   52 Compressor stop control unit     -   53 Cold water temperature control unit     -   6 Host control device     -   61 Control unit     -   611 Compressor start/stop permission output unit     -   612 Unit number control unit 

1.-6. (canceled)
 7. A refrigerating system comprising: a plurality of parallel type refrigerators each of which has a plurality of compressors; and a host control device having a compressor start/stop permission output unit which is configured to output a compressor activation permission or a compressor stop permission to one of the plurality of parallel type refrigerators according to an output mode indicating a type of output required for all of the plurality of parallel type refrigerators and a predetermined permission condition, wherein the compressor start/stop permission output unit determines to which of the parallel type refrigerators that is activated the compressor activation permission is output and to which of the parallel type refrigerators that is stopped the compressor activation permission is output according to the output mode, and each of the parallel type refrigerators includes a compressor activation control unit which is configured to activate a stopped compressor included in a certain refrigerator when a load factor of the certain refrigerator is equal to or greater than a first specified value and the compressor activation permission is received, and a compressor stop control unit which is configured to stop an activated compressor included in a certain refrigerator when the load factor of the certain refrigerator is less than a second specified value and the compressor stop permission is received.
 8. The refrigerating system according to claim 7, wherein the compressor start/stop permission output unit is able to output the next compressor activation permission or compressor stop permission after a predetermined activation permission waiting time or stop permission waiting time has elapsed when the compressor of the parallel type refrigerator is activated or stopped according to the compressor activation permission or the compressor stop permission.
 9. The refrigerating system according to claim 8, wherein the host control device further includes a unit number control unit which is configured to activate or stop a main body of each of the parallel type refrigerators according to an output required for all of plurality of parallel type refrigerators, when the main body is activated or stopped, the unit number control unit is able to activate or stop the next main body after measurement of a predetermined stage increase prohibition time or stage decrease prohibition time ends, and the measurement of the stage increase prohibition time or the stage decrease prohibition time is reset when the compressor of the parallel type refrigerator is activated or stopped according to the compressor activation permission or the compressor stop permission.
 10. The refrigerating system according to claim 9, wherein the activation permission waiting time and the stop permission waiting time are shorter than the stage increase prohibition time and the stage decrease prohibition time.
 11. The refrigerating system according to claim 7, wherein: the compressor start/stop permission output unit is configured to output the compressor activation permission to the parallel type refrigerator having the highest priority among the parallel type refrigerators in which one or more of the compressors are not activated and output the compressor stop permission to the parallel type refrigerator having the lowest priority among the parallel type refrigerators in which two or more of the compressors are not activated, when a predetermined malfunction occurs in the parallel type refrigerator which is activated, the priority of the parallel type refrigerator is set to be the lowest among the parallel type refrigerators which are activated, and when a predetermined malfunction occurs in the parallel type refrigerator which is stopped, the priority of the parallel type refrigerator is set to be the lowest among the parallel type refrigerators which are stopped.
 12. A refrigerating system control method using a plurality of parallel type refrigerators each of which has a plurality of compressors, and a host control device having a compressor start/stop permission output unit which is configured to output a compressor activation permission or a compressor stop permission to one of the plurality of parallel type refrigerators according to an output mode indicating a type of output required for the whole of the plurality of parallel type refrigerators and a predetermined permission condition, wherein the compressor start/stop permission output unit determines to which of the parallel type refrigerators that is activated the compressor activation permission is output and to which of the parallel type refrigerators that is stopped the compressor activation permission is output according to the output mode, and in each of the parallel type refrigerators, a stopped compressor included in a certain refrigerator is activated by a compressor activation control unit when a load factor of the certain refrigerator is equal to or greater than a first specified value and the compressor activation permission is received, and an activated compressor included in a certain refrigerator is stopped by a compressor stop control unit when the load factor of the certain refrigerator is less than a second specified value and the compressor stop permission is received. 